Mama anauzia wateja mboga sokoni.

It can be analyzed like this:

• a- = he/she
• -na- = present-time marker, often translated as is ...-ing or simple present
• -uz- = verb root sell
• -i- = applicative extension, which adds the idea of to/for someone
• -a = final vowel

So anauzia means something like she is selling to/for.

This is why the sentence can include both:

• the person receiving the goods: wateja
• the thing being sold: mboga

Because anauzia specifically means sell to/for someone, while anauza just means sell in a more general way.

Compare:

• Mama anauza mboga sokoni.
  = Mother/the woman is selling vegetables at the market.

• Mama anauzia wateja mboga sokoni.
  = Mother/the woman is selling vegetables to customers at the market.

The -i- applicative part makes the recipient (wateja) part of the verb’s structure.

Because with an applicative verb like anauzia, the recipient often comes directly after the verb.

So the structure is roughly:

• Mama = subject
• anauzia = is selling to
• wateja = customers
• mboga = vegetables
• sokoni = at the market

A very natural pattern here is:

Subject + verb + recipient + thing + location

That is why wateja comes before mboga.

Because the idea of to/for is already built into the verb anauzia.

In English, you need a separate word like to:

• sell vegetables to customers

In Swahili, the verb itself can carry that meaning:

• anauzia wateja mboga

So wateja does not need kwa here.

Yes. That is also possible.

For example:

• Mama anauza mboga kwa wateja sokoni.

This uses the basic verb anauza (is selling) plus kwa wateja (to customers).

The sentence in your example uses a different but very common strategy:

• anauzia wateja mboga

So both patterns are possible:

• anauza mboga kwa wateja
• anauzia wateja mboga

The second one is especially useful because the verb itself directly includes the recipient idea.

The singular is mteja = customer.

So:

• mteja = customer
• wateja = customers

This is a common human noun pattern in Swahili:

• singular m-
• plural wa-

For people, the verb agreement usually follows the same human/animate pattern.

In many contexts, mboga is used as a collective or mass-type noun meaning vegetables or greens.

So even though English makes a strong singular/plural distinction, Swahili often uses mboga as a general word for vegetable produce or cooked greens.

Depending on context, it can feel like:

• vegetables
• greens
• sometimes a vegetable dish

So in this sentence, mboga is naturally understood as vegetables.

Soko means market.

When you add -ni, it makes it locative:

• soko = market
• sokoni = in/at the market

So -ni often gives the meaning in, at, or to a place, depending on context.

Examples:

• nyumbani = at home
• shuleni = at school
• sokoni = at the market

-na- is the present tense marker.

Depending on context, it can be translated in English as:

• is selling
• sells

So Mama anauzia wateja mboga sokoni could mean:

• Mother is selling vegetables to customers at the market or
• Mother sells vegetables to customers at the market

If there is no extra context, English often chooses is selling, but Swahili -na- can cover both present ongoing and general present meanings.

Because Swahili normally does not use articles like English a, an, or the.

So:

• Mama can mean mother, the mother, a mother, Mom, or the woman, depending on context.
• wateja can mean customers or the customers
• mboga can mean vegetables or the vegetables

You figure out the most natural English choice from the situation, not from a separate word in Swahili.

Swahili word order is fairly flexible, but this sentence uses a very natural default order.

The version here is straightforward and neutral:

• Mama anauzia wateja mboga sokoni.

That said, speakers may change the order for emphasis, topic, or style. For a learner, though, this sentence is an excellent model to follow.

A good basic pattern to remember is:

Subject + verb + recipient + thing + place

Because the full noun objects are already stated after the verb.

In Swahili, object markers are often used when:

• the object is a pronoun,
• the object is already known from context,
• or the speaker wants extra emphasis/topicality.

Here, the sentence is perfectly complete without one:

• Mama anauzia wateja mboga sokoni.

If the customers had already been mentioned, Swahili might use an object marker to refer back to them, but that is not necessary in this sentence.

Not always. Mama can mean:

• mother / mom
• a respectful way to refer to an adult woman
• sometimes simply the woman, depending on context

So the exact English choice depends on the situation. Swahili often relies on context more than English does for this kind of word.